Context: The assessment and management of sport-related concussion can be very challenging given the often-inconsistent injury presentation and variable recovery time associated with this injury. Despite high prevalence rates in adolescent and college-aged athletes, attention deficit hyperactivity disorder (ADHD) has received little empirical attention in the sport-concussion literature. Thus additional data on the effects of ADHD on concussion outcomes is needed. Objective: The purpose of this study was to compare changes in neurocognitive performance and symptom reports following sport-related concussion between concussed athletes with and without ADHD. Design: Prospective cohort study. Setting: This study was performed in a controlled laboratory and field setting. Patients or Other Participants: A total of 122 concussed athletes volunteered to participate in the study (61 ADHD: age = 17.6 + 2.8 years, height = 168.0 + 46.2 cm, mass = 79.8 + 30.9 kg, 61 No ADHD: age = 17.6 + 2.6 years, height = 172.0 + 33.4 cm, mass = 83.7 + 24.7 kg). Intervention(s): The independent variables were concussion group (ADHD vs No ADHD) and time of assessment (baseline, 2, 7 days post-injury). Participants completed the Immediate Post-concussion Assessment and Cognitive Test (ImPACT), Postconcussion Symptom Scale (PCSS), and self-reported if they had ADHD at baseline; and at 2 and 7 days postconcussion. A series of 2 group (ADHD vs No ADHD) X 3 time (baseline, 2, 7 days) repeated measures ANOVA were performed for each of the four ImPACT composite scores and the four symptom clusters. Main Outcome Measure(s): Dependent variables included ImPACT composite scores (verbal/ visual memory, reaction time, processing speed) and symptom clusters (cognitive-migraine-fatigue, somatic, sleep, affective). Separate ANOVAs with Bonferroni correction and post-hoc means comparisons were performed using Tukey’s HSD. A bonferroni-corrected p value was set p = .01 to control for multiple comparisons. Results: There were no group by time significant interactions for verbal memory ([ADHD: NoADHD] M = 78.3 + 14.9: M = 81.6 + 12.1 p = .23), visual memory (M = 66.5+14.7:M=68.5+14.3p=.59), motor processing speed (M = 37.3 + 8.7:M=38.4+8.6p=.45), and reaction time (M = .59 + .08: M = .58 + .09 p = .22). There were also no group by time significant interactions for cognitive-migraine-fatigue cluster (M = 5.4 +7.2:M=3.9+7.1p=.96), somatic cluster (M = .61 + 1.6: M = .39 + 1.3 p = .52), affective cluster (M = .11 + .64: M=.10+.45p=.85), and the sleep cluster (M = .85 + 2.1: M = .52 + 1.6 p = .76). Conclusion: Overall this study suggests that there are no differences on post-concussion neurocognitive performance and symptoms between concussed athletes with and without ADHD. Although clinicians believe that ADHD is a ‘moderating’ variable in sports-related concussion management, results from our study suggest they have no effect on an athletes’ cognitive function following concussive injury.